Lumber prices have jumped in the past month, as wildfires in Canada raise concerns about supply disruptions while healthy U.S. housing starts boost the demand side. Cash prices have climbed 22% since June 1. They settled last week at US$420 for 1,000 board feet of two-by-fours made from Western spruce, pine and fir, compared with US$343 on June 1, according to Random Lengths. …Key factors that dampened supplies last month included the impact of wildfires in Canada, the lingering effects of previous decisions by producers to reduce B.C. output, and slowing European wood shipments into the U.S. On the demand side, stronger-than-expected data released in mid-June on U.S. housing starts helped bolster the market. …On the Chicago Mercantile Exchange, prices for lumber futures for November delivery rose US$5 to close on Friday at US$555 for 1,000 board feet. That’s up 7% since June 1. [to access the full story a Globe & Mail subscription is required]